Sales of Used Car by a company held as fixed Asset - Goods and Services Tax - GST

Sir/Madam, Our company is preparing to sell one of the used cars recorded in the books as a fixed asset. By applying the marginal scheme, the selling price (10000) is less than the written down value (WDV) of 15,000, resulting in a negative margin (5000). Our Doubt For the purpose of billing, either an Tax invoice or a bill of sale is to be issued? Procedure for filing GSTR-1 for the specified sale? Regards, Senthilkumar